INFLUENCE OF THE CRYSTALLIZATION PROCESS ON THE INTERNAL FRICTION OF SOME OXIDE GLASSES.

The influence of phase separation and crystallization on the internal friction of some oxide glasses is reviewed. In alkali-containing glasses, the internal friction peak caused by stress-induced diffusion of alkali ions decreases and shifts to higher temperature slightly due to phase separation. In alkali-free glasses phase separation only exerts a minor decrease upon the background of internal friction curves, whereas crystallization influences the internal friction of these glasses more strongly. Because of crystallization, in alkali-containing glasses alkali ions might diffuse in a residual glass phase and a crystal phase, respectively. This might cause corresponding internal friction peaks. In alkali-free glasses, no evident internal friction peak is observed. However, the author found a high and wide internal friction peak at about 100 degree C in the crystallized MgO multiplied by (times) Al//2O//3 multiplied by (times) SiO//2 multiplied by (times) TiO//2 and ZnO multiplied by (times) Al//2O//3 multiplied by (times) SiO//2 multiplied by (times) ZrO//2 glasses. The peak occurring in the two glasses studied is probably connected with glass crystallization and crystallized crystals.